MC68HC908AS32A Datasheet, PDF (60/280 Pages) Freescale Semiconductor, Inc – Microcontrollers

Analog-to-Digital Converter (ADC)
M68HC08 CPU
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
CONTROL AND STATUS REGISTERS
USER FLASH — 32, 256 BYTES
USER RAM — 1024 BYTES
USER EEPROM — 512 BYTES
MONITOR ROM — 256 BYTES
USER FLASH VECTOR SPACE — 52 BYTES
OSC1
OSC2
CGMXFC
CLOCK GENERATOR
MODULE
RST
SYSTEM INTEGRATION
MODULE
IRQ
IRQ MODULE
V_REFH
ANALOG-TO-DIGITAL
MODULE
BREAK MODULE
LOW-VOLTAGE INHIBIT
MODULE
COMPUTER OPERATING
PROPERLY MODULE
6-CHANNEL TIMER
INTERFACE MODULE
PROGRAMMABLE INTERRUPT
TIMER MODULE
SERIAL COMMUNICATIONS
INTERFACE MODULE
SERIAL PERIPHERAL
INTERFACE MODULE
BYTE DATA LINK CONTROLLER
PTA7–PTA0
PTB7/ATD7–
PTB0/ATD0
PTC4
PTC3
PTC2/MCLK
PTC1–PTC0
PTD6/ATD14/TCLK
PTD5/ATD13
PTA4/ATD12
PTD3/ATD11–
PTD0/ATD8
PTE7/SPSCK
PTE6/MOSI
PTE5/MISO
PTE4/SS
PTE3/TCH1
PTE2/TCH0
PTE1/RxD
PTE0/TxD
PTF3/TCH5–
PTF0/TCH2
POWER-ON RESET
MODULE
BDRxD
BDTxD
V_SS
V_DD
V_DDA
V_SSA
POWER
AV_SS/V_REFK
V_DDAREF
Figure 3-1. Block Diagram Highlighting ADC Block and Pins
3.3.2 Voltage Conversion
When the input voltage to the ADC equals V_REFH (see 19.7 Analog-to-Digital Converter (ADC)
Characteristics), the ADC converts the signal to $FF (full scale). If the input voltage equals V_SSA, the ADC
converts it to $00. Input voltages between V_REFH and V_SSA are a straight-line linear conversion.
Conversion accuracy of all other input voltages is not guaranteed. Avoid current injection on unused ADC
inputs to prevent potential conversion error.
NOTE
Input voltage should not exceed the analog supply voltages.
MC68HC908AS32A Data Sheet, Rev. 2.0
60
Freescale Semiconductor